Red phosphor and luminous element using the same

Abstract

The present invention relates to a phosphor and a luminous element using the same. The present invention provides a phosphor for absorbing a portion of light emitted from a light source and emitting light with a wavelength different from that of the absorbed light. The phosphor comprises a fluorescent material having an alkaline earth metal-germanium metal-sulfur structure that contains Ge and at least one element selected from the group consisting of Sr and Ca and is activated by Eu. The phosphor of the present invention increases a color rendering index (CRI) of a white luminous element for a general lighting apparatus, and a luminous element using the phosphor has an advantage in that it is suitable for a white luminous element backlight which can substitute for a cold cathode fluorescent lamp (CCFL) in medium and large-sized TVs and has higher color reproducibility and higher white uniformity.

1. A phosphor for absorbing a portion of light emitted from a light source and emitting light with a wavelength different from that of the absorbed light, the phosphor comprising:
 a fluorescent material having an alkaline earth metal-germanium metal-sulfur structure that contains Ge and Ca and is activated by Eu, 
 wherein the phosphor is represented by a general formula of A (x-a) Eu (a) GeS (z) , and 
 wherein ‘A’ is at least one element selected from the group consisting of Sr and Ca, ‘x’ satisfies 2.5≦x≦4, ‘a’ satisfies 0.001≦a/x≦0.01 and ‘z’ satisfies z=x+2. 
 
     
     
       2. A luminous element, comprising:
 a light emitting diode; and 
 a phosphor according to  claim 1 . 
 
     
     
       3. The luminous element as claimed in  claim 2 , wherein the light emitting diode emits ultraviolet rays or blue light. 
     
     
       4. The luminous element as claimed in  claim 2 , wherein the luminous element is a white luminous element that has the light emitting diode capable of emitting blue light and further comprises a green light phosphor. 
     
     
       5. The luminous element as claimed in  claim 4 , wherein the green light phosphor includes (Ba,Sr,Ca) 2 SiO 4 :Eu. 
     
     
       6. The luminous element as claimed in  claim 4 , wherein the green light phosphor includes SrGa 2 S 4 :Eu. 
     
     
       7. The phosphor as claimed in  claim 1 , wherein the fluorescent material further contains Sr, wherein the Sr is partially substituted by Ca and partially substituted by Eu. 
     
     
       8. A phosphor represented by a general formula of A (x-a) Eu (a) GeS (z) , wherein ‘A’ is at least one element selected from the group consisting of Sr and Ca, ‘x’ satisfies 2.5≦x≦4, ‘a’ satisfies 0.001≦a/x≦0.01 and ‘z’ satisfies z=x+2. 
     
     
       9. The phosphor as claimed in  claim 8 , wherein ‘x’ satisfies 2.5≦x≦3.5 and ‘a’ satisfies 0.003≦a/x≦0.007. 
     
     
       10. A luminous element, comprising:
 a light emitting diode; and 
 a phosphor according to  claim 9 . 
 
     
     
       11. A luminous element, comprising:
 a light emitting diode; and 
 a phosphor according to  claim 8 . 
 
     
     
       12. The phosphor as claimed in  claim 8 , wherein ‘A’ consists of Sr and Ca, the Sr partially substituted by Ca and partially substituted by Eu.